Well, I'm not sure that I follow you. The power to the ignition switch comes from the battery, through a fuse, it does not come from the regulator. The ign switch provides battery power TO the regulator, which in turn provides current to the brushes in the alternator. The output of the alternator goes through the rectifier diodes and then through the main fuse to the battery.
So, as long as your battery is capable of producing enough current to keep the headlight on and power the coils, you can continue riding, at least to head home and fix the problem.
If the alternator or regulator or rectifier fail, then you should disconnect the regulator so it is not drawing current uselessly, thus keeping whatever is in the battery available for the headlight and coils.
There have been a lot of posts that talk about how long your battery will last if the alternator fails, but the only sure way to know is to try it. Disconnect the regulator and see how long the engine runs. Ride around the block a few times so you are close to home when it quits. Recharge the battery with a trickle charger after the test. Subtract about 15 minutes from the time, because that is about how long it will take for you to even realize that the alternator has quit.
Last Edit: Aug 7, 2007 10:59:29 GMT -5 by pamcopete
Thanks for the clarification. For some reason, I thought you diagram above meant the ignition switch was getting power from the regulator vs the switch providing power to the VR. Now it makes sense. Sorry for the dumb question. I really appreciate your posts-very helpful.
Well, the diagram could be a little confusing, so I changed it to read "from Ign Switch" with the arrow going the other way. Also added the note that the output from the rectifier must go through a fuse to the battery.
Last Edit: Aug 7, 2007 14:23:01 GMT -5 by pamcopete
Probably only confusing to me but thanks for the clarification. What indications would occur that the alternator/VR/rectifier has failed? It seems the failure would be transparent to the rider (until the lights begin to dim for a points ignition) unless an idiot light, voltmeter, or ammeter was in the system to indicate a problem. I did not plan to add any of those to my system but I am thinking an idiot light showing a battery discharge versus charge situation could be useful. Now, I just need to figure out how to add this light to the system.
What amp fuse would you recommend between the VR and battery and also in the main wire from the battery to the ignition switch?
Well, the main fuse should be a 20 A fuse, just like stock. I would also recommend a separate 20 amp fuse from the rectifier to the battery, so if it blows, you will still have power from the battery.
A meter would be useful because you are going to have to keep an eye on that tiny battery when stooped at a light.
This is the meter I installed on my bike with a bracket fashioned from a piece of aluminum angle screwed under the idiot light housing. It's from www.martelcorp.com I also wired a diode to my safety relay so the white headlight lamp comes on if the charging system fails. If you were not planning on using the safety relay, you could use it to turn on a lamp when the alternator is not working.
Last Edit: Aug 7, 2007 15:23:28 GMT -5 by pamcopete
I'm building the wiring harness from scratch so I will need to look at a wiring diagram to see the safety relay. What is the location and purpose of the safety relay in the stock system?
I haven't seen any simplified XS650 wiring diagrams that have the idiot light so I may need to get creative for that one. I think I need a light that comes on when the sytem voltage drops below a certain point (12.5 volts or so) but I'm not sure how to make that happen. Maybe a relay that requires 12.5-13 volts to remain open so that a voltage drop below that would allow the relay to close and make a connection (ground or power side) for a small bulb or an LED.
In the stock setup, the safety relay operates from the yellow wire from the alternator when the alternator is producing an output. It supplies battery voltage to the starter relay when the alternator is not producing an output, IE the engine isn't running, so prevents you from engaging the starter when th engine is running. And it turns on the headlight after the engine has started. If you connected a lamp to the contact that normally provides battery to the starter relay, then the lamp would come on if the regulator, rotor or stator failed, but it is not sensitive to battery voltage.
Last Edit: Aug 7, 2007 18:28:02 GMT -5 by pamcopete
If I understand correctly, I should be able to connect the yellow wire from the alternator to a idiot light and the light would only be lit when the alternator is not producing output. I will give it a shot and see what happens.
No, no....just the opposit.....the yellow wire has a very small AC voltage when the alternator IS running and producing an output, so you have to have the safety relay to turn the light off when the alternator is producing an output.
Last Edit: Aug 8, 2007 5:28:56 GMT -5 by pamcopete
could you look at this rough sketch of what im shooting for. I had to scan this at work so its a rough sketch , not the normal quality crayola drawings I normally do. ;D ;D no elect start, no keyed switch. thanks jeep.
sorry about the small pic, im not really good at scanning . also the on off switch is simplified in sketch, im planning on using a really cool antique tractor switch thats got 3 positions, but ive got to figure out that part too, I wasnt sure if fuse is before or after switch.
Last Edit: Aug 9, 2007 12:57:54 GMT -5 by pamcopete
Here is another wiring diagram for the Reg/Rect. Hope it makes it more understandable
I can then attach fuse @ brown wire to acc's and then this goes to coil? the X where the ig switch would be is replaced with on/off switch. (i will also hide a kill switch in a top secret spot) that sheds some light on it I couldnt figure out where power was coming from.
r80rt: :)This is a splendid write up, THANK YOU!!!!
Dec 26, 2015 16:54:05 GMT -5
mashermoto: What the what is this shoutbox for? Or should I shout, WHAT THE WHAT IS THIS SHOUTBOX FOR!
May 12, 2016 22:22:21 GMT -5
motormike: Good Day ...just a FYI.. Wild Cat is this Labor Day weekend. Still go'n on. A few 650's still make the scene. Various rides at different skill levels each day.. awards dinner sunday eve. BS in the park'n lot after dinner.
Aug 23, 2016 7:57:01 GMT -5
lsettle: First post in over 6 years!
Aug 28, 2016 19:45:17 GMT -5
kardon: Wow quiet here, where did they all go.
Oct 7, 2016 2:18:13 GMT -5
gggGary: XS650.com LOL
Feb 16, 2017 20:49:02 GMT -5
buell88: Anybody have any idea who built the xs650 tracker used in the Draggin Jeans Ad on Pipeburn?
May 16, 2017 16:24:09 GMT -5
joshua: The regulator/rectifier unit I got from Mikes PMA has closer hole spacing than original. Are we supposed to mill the holes to fit?
Jun 7, 2017 19:25:58 GMT -5
joshua: My bad. I found the bracket they supplied to mount the rectifier/regulator... Uh oh. How is this meant to work? Which way is it meant to mount? Looks like I have to use some spacers or something. Good instructions would be nice.
Jun 7, 2017 22:09:52 GMT -5
craig8johnson: Not sure if this is the right spot or not but oh well...
Jul 11, 2017 18:04:15 GMT -5
craig8johnson: I'm checking the charging system. I'm afraid I might have fried the last battery. With the solid state regulator (after market) what should it be charging at. The book says, I think, 15 volts. I'm hitting 17 when revved. Is that too high?
Jul 11, 2017 18:06:19 GMT -5
gggGary: Yes 17 volts is too high, about 14 volts is max, sounds like you don't have the right regulator or it's wired wrong.
Jul 13, 2017 6:54:33 GMT -5
dean: Just saying Hello, new member who is going to fix up a 79 XS650 that has seen its better days. I will definitely have lots of questions coming up.
Jun 23, 2018 16:45:32 GMT -5
tt650: Trying to breathe life into a 1980 that's been stored (indoors) for 25 yrs. Air filters are dry rotted. Have cleaned carbs but she only runs briefly on choke then stops. Need jet setting info and other ideas that might help her idle and rev.
Jul 3, 2018 19:15:19 GMT -5
trix13: Hey everyone! New to the forum and am fighting those gremlins!! New charging system, ignition switch, coil and fuse box. Resistance is higher than normal on the ignition pick up so I'm trying to find one. No such luck yet.
Aug 16, 2018 8:50:48 GMT -5
trix13: Also, even though all of my connections are clean, I cannot seem to find out why , when at higher rpms, I hit the signals and the rpms pulse with the signals...hahah. same with the brake light. I appreciate all input!!
Aug 16, 2018 8:55:08 GMT -5
bob99: how do I post a question. I am new to the forum
Jun 6, 2019 10:52:10 GMT -5
adlpc: Hello all! Been enjoying your edifying posts and discussions - and as a fan of the XS650 since my early teenage years happy that I now own a 1980 Special which I plan to turn into a vintage half faired racer. Thank you all for being here!
Oct 1, 2019 0:58:56 GMT -5
jimothyj: Hello everyone, I just joined & wish would have known about this site in 2014 when I brought my 1974 TX650A back from the grave. I have spent a good deal of $$ and alot of time on it. Just painted it and working on electrical, I will post pics soon,
Apr 10, 2021 2:14:13 GMT -5
louisvan: trix13 - I had a problem with my 1975 SX650. When I got to highway speeds, the engine lost power. The problem was in the connectors. At a certain vibration and the wind pushing on the wiring loom, the connector lost continuity. A bad crimp to the wire.
May 20, 2021 1:19:09 GMT -5